Adding slides to previous section - Beamer

My presentation is consisted of 4 consecutive slides. I want to divide them in 2 sections. My code:

    \documentclass{beamer}
\mode<presentation>
{\usetheme{Frankfurt}
\usecolortheme{lily}
\usefonttheme{professionalfonts}}
\usepackage[english]{babel}
\setbeamertemplate{footline}[frame number]

\begin{document}

\section{Numerical examples}
\begin{frame}
Example 1
\end{frame}

\section{Results}
\begin{frame}
Results 1
\end{frame}

\section{Numerical examples}
\begin{frame}
Example 2
\end{frame}

\section{Results}
\begin{frame}
Results 2
\end{frame}

\end{document}


I have something like this:

Because they have the same names, I would like to achieve the following results:

How can I add slide to the previous section?

• I am confused. You have four \section commands and yet you say you only want two sections? I don't understand what you are trying to do; if you just want two sections, use only two \section commands. – Gonzalo Medina Jul 30 '14 at 18:40

USe only two \section command and also the possibility of a title for the frame:

\documentclass{beamer}
\usetheme{Frankfurt}
\usecolortheme{lily}
\usefonttheme{professionalfonts}
\usepackage[english]{babel}
setbeamertemplate{footline}[frame number]

\begin{document}

\section{Numerical examples}
\begin{frame}
Example 1
\end{frame}

\begin{frame}{Results}
Results 1
\end{frame}

\section{Numerical examples}
\begin{frame}
Example 2
\end{frame}

\begin{frame}{Results}
Results 2
\end{frame}

\end{document}